feat: Windows compatibility, model selector, stop button & smart model tips

[nekdima]

Summary

Adds full Windows support, model selector UI, stop button for cancelling responses, human-readable tool progress cards, and smart model recommendation tips. Supersedes #2.

Changes

Windows Compatibility

SDK dependency

• Switched @github/copilot-sdk\ from local \ile:\ path to published ^0.1.32\ on npm
• Added \postinstall\ script that patches \�scode-jsonrpc\ exports map for ESM compatibility

Native messaging host (\src/host/host.mjs)

• Cross-platform copilot CLI resolution: \where copilot.exe\ on Windows, well-known paths on macOS/Linux
• Falls back to SDK-bundled CLI when system CLI is not found
• Portable shebang (#!/usr/bin/env node) instead of hardcoded Homebrew path
• Platform-aware PATH injection
• Added \�pproveAll\ for permission requests

Windows launcher

• New \src/host/host-wrapper.bat\ — Chrome/Edge on Windows requires a .bat/.exe\ as the native messaging host path
• Updated \scripts/register-host.bat\ to register the wrapper instead of the .mjs\ file directly

Model Selector Feature

New component (\src/panel/components/ModelSelector.tsx)

• Dropdown in the panel header to choose the AI model
• Fetches available models from SDK via \client.listModels()\ on init
• Model selection persisted in \localStorage\ across sessions

Message flow

• New \AVAILABLE_MODELS\ message type from host → service worker → panel
• Model passed with each \SEND_CHAT_MESSAGE\ for per-request selection
• \setModel\ is best-effort: failure doesn't block the user's message
• Model list cached in service worker so late-connecting panels receive it
• Serialized message handling in host with promise queue to prevent races

Stop Button (NEW)

• Red ■ stop button replaces send button during streaming/tool execution
• Sends \CANCEL_REQUEST\ through Panel → service-worker → native host → session.cancel()
• Persists throughout the entire multi-step workflow using deferred loading-off pattern (500ms timer)
• \TOOL_CALL_START\ and \CHAT_RESPONSE_CHUNK\ cancel the off-timer, keeping stop visible

Smart Model Recommendation Tips (NEW)

• New \ModelRecommendation.tsx\ component analyzes prompt text as user types (debounced 600ms)
• Classifies prompts as code/complex/simple and recommends the optimal model
• Tip banner appears above chat input with Switch/Dismiss buttons
• Matches available models against a tier system (quality, speed, code categories)

Human-Readable Tool Progress Cards (NEW)

• Tool call cards show friendly labels with icons (e.g. 📄 'Reading page content' instead of \get_page_html)
• Animated progress bar on active tool calls instead of static emojis
• All 20+ browser tools have descriptive labels and contextual icons

Version bump

• Extension version bumped to 0.3.0

Files Changed (18 files)

• \manifest.json\ — version bump
• \package.json\ / \package-lock.json\ — SDK from npm, postinstall, version bump
• \scripts/patch-vscode-jsonrpc.mjs\ — new ESM patch script
• \scripts/register-host.bat\ — points to wrapper
• \src/host/host-wrapper.bat\ — new Windows launcher
• \src/host/host.mjs\ — platform-aware CLI, model listing, serialized messages, CANCEL_REQUEST handler
• \src/background/service-worker.ts\ — model caching, forwarding, CANCEL_REQUEST forwarding
• \src/panel/components/ModelSelector.tsx\ — model dropdown component
• \src/panel/components/ModelRecommendation.tsx\ — NEW smart model tip component
• \src/panel/components/HeaderBar.tsx\ — integrates model selector
• \src/panel/components/ChatInput.tsx\ — stop button, onInputChange for recommendations
• \src/panel/components/ToolCallCard.tsx\ — human-readable labels, progress bars
• \src/panel/App.tsx\ — model state, stop handler, recommendation wiring, persistent loading state
• \src/panel/lib/copilot-client.ts\ — model param, cancelRequest
• \src/panel/styles/panel.css\ — progress pulse and slide-up animations
• \src/shared/messages.ts\ — new message types (CANCEL_REQUEST)
• \src/shared/types.ts\ — ModelInfo type

Testing

• Verified on Windows 11 + Edge: native host connects, model selector populates, chat works with model switching
• Stop button persists through multi-step tool call workflows
• Model recommendation tip appears for code/complex/simple prompts
• Extension builds cleanly (Vite, 306 modules, 1.2s)
• macOS/Linux paths remain unchanged